Process for the treatment of petroleum



United States Patent p 3,125,509 PROCESS FOR THE TREATMENT OF PETROLEUMDISTILLATES Bernard Laine and Charles Vernet, Lavera par Martigues,Bouches-du-Rhone, France, assignors to The British Petroleum CompanyLimited, London, England, a British joint-stock corporation No Drawing.Filed Oct. 26, 1960, Ser. No. 64,986 Claims priority, application FranceOct. 26, 1959 11 Claims. (Cl. 208-264) This invention relates to thetreatment of distillate petroleum fractions boiling above 150 C. andparticularly to the treatment of distillates boiling between 150 and 450such as 150-250 C., 25 0350 C. and 350450 C. distillates, and the theprincipal object of the invention is to provide a process by means ofwhich the pour point and cloud point of such fractions may besubstantially lowered.

According to the process of the present invention, the distillate iscontacted in the presence of hydrogen with a catalyst havingdehydrogenating and/ or cracking activity and comprising asilica-alumina base, at a temperature of at least 400 C. but below thetemperature at which substantial cracking occurs, a pressure of at least100 p.s.i.g., and a space velocity of the liquid feedstock not exceeding30 v./v./hr., the temperature and space velocity being correlated sothat the pour point of the stabilized distillate is at least 5 C. lowerthan the pour point of the feedstock.

For the purposes of the present specification, substantial cracking isunderstood to occur when more than 20% wt. of the feedstock is convertedto material boiling below 150 C. Preferably not more than 15% wt. of thefeedstock is converted to material boiling below 150 C. The temperatureemployed will not usually exceed 480 C. and in general the lower thetemperature, the lower the space velocity.

The pressure employed will normally be between 100 and 1500 p.s.i.g. andthe hydrogen to hydrocarbon mole ratio will normally be from 5 to 1 to20 to 1.

In general, it is preferred to operate under conditions which result inan overall consumption of hydrogen, since such method of operationincreases catalyt life, and to achieve such overall consumption ofhydrogen it is necessary to operate at a pressure above the equilibriumpressure of the feedstock, i.e. the pressure obtainable by recycling thehydrogen produced at a particular combination of temperature and spacevelocity, no extraneous hydrogen being added after start-up.

A further advantage of operating with an overall consumption of hydrogenis that a reduction of the diesel index is minimized or avoided.

In some cases, however, it may be desired to reduce the pour point ofthe distillate without substantially reducing its specific gravity, andin these cases it is necessary to operate under conditions in which nohydrogen is consumed, i.e. at or below the equilibrium pressure asdefined above.

Hydrogen may be added on a once-through basis, or it may be recycled.

The distillate fraction used as feedstock may have a low initial sulfurcontent, for example 0.1% wt. sulfur or less. Such low sulfur feedstocksmay be straight-run materials or the products of previous refiningtreatments, for example, products of a hydrocatalytic desulfurizationprocess. With'feedstocks containing higher amounts of sulfur, theprocess according to the invention may result in aconsiderable reductionin the sulfur content. In the case of feedstocks having a low initialsulfur content, the process may be accompanied by an increase inspecific gravity.

35,125,509 Patented Mar. 17, 1964 Some lower boiling material will beproduced by, for example, dehydrogenation, desulfurization and/ or asmall amount of cracking, and this is separated from the product,preferably by fractionation, to stabilize it and give a material of therequired boiling range and flash point. A convenient cut point is in theregion of 170 C.

Particularly effective catalysts for the purposes of the presentinvention consist of molybdenum trioxide, M00 supported on asilica/alumina base, and a mixture of molybdenum trioxide, M00 andcobalt oxide, CoO, supported on a silica/alumina base.

It has been found that the presence of cobalt oxide, C00, is notnecessary for achieving the desired reduction of the pour point but isessential if simultaneous desulfurization of the feedstock is required.Thus, in treating a sulfur-free feedstock or in treating asulfur-containing feedstock when it is not necessary to remove sulfur, aparticularly effective catalyst may have the following composition bywt.

Percent Molybdenum trioxide, M00 5-15 Silica, SiO 5-l4 Alumina BalanceWhen it is desired to desulfurize the feedstock as well as reduce itspour point, the catalyst may have the following composition by weight:

Percent Molybdenum trioxide, MoO 5-15 Cobalt oxide, CoO .2-1 Silica, Si0514 Alumina Balance The optimum content of molybdenum trioxide appearsto-be Ill-11% and the optimum molar ratio of the metals Co to M0 appearsto be .1.

The ratio of cobalt to molybdenum necessary to produce the desiredreduction in the sulfur content is considerably less than in the case ofconventional cobalt molybdate catalysts used for desulfurization. Thismay be due to the fact that more severe process conditions, i.e. highertemperature and pressure and lower space velocity, are required toproduce the desired reduction in the pour point.

it has been found that the use of a catalyst having a silica/ aluminabase enables a particular reduction in pour point to be effected at alower temperature than is possible with a catalyst supported on analumina base. The use of lower temperatures means that it is possible touse a lower hydrogen to hydrocarbon ratio, thereby reducing the cost ofthe process.

Experiments were carried out with four catalysts having the followingcompositions by weight.

On a base consisting of silica-free alumina.

These catalysts were used to treat a gas oil having a sp. gr. of 0.850and a pour point of -1 C. under the following conditions.

'3 it) Temperature (catalysts Nos. 1

and 2) 420, 440 and 450 C. Pressure (catalyst No. 3),

40 kg./cm. 420, 450 and 480 C. Space velocity 1 v./v./hr.

Hydrogen to hydrocarbon ratio 10/ 1.

In order to maintain the hydrogen partial pressure at the desired level,it is necessary progressively to increase the total pressure since thereaction produces gas and consumes hydrogen.

Satisfactory operation over a period of 600 hours has been achieved onthe light gas oil at a constant total pressure of 780 p.s.i. since, asthe hydrogen consumption was small, the hydrogen partial pressure fellonly from 570 to 500 p.s.i.

On the other hand, when treating the heavy gas oil at a fixed totalpressure of 1000 p.s.i., the hydrogen partial pressure fell from 800p.s.i. to 550 p.s.i. after 420 hours and pour conversion was thenobtained at 460 C. Improved operation may be achieved by maintaining the7 hydrogen partial pressure at 800 p.s.i. by progressively Table 1Temperature, C 420 440 450 480 Catalyst No 1 2 3 1 2 1 2 3 3 FeedstockSpecific Gravity at 15 C 0.850 O. 829 0.829 0. 835 0. 827 0. 827 0. 8200.825 0. 824 0. 816 Pour Pint, C. l 13 16 7 -22 -22 -22 -22 22 CloudPoint, (1. 7 7 3 14 21 19 19 Total Sulfur, Percent Wt. 1. 2 0. O01 0.001 0. 001 0. 001 0. 001 0. 001 0. 001 0. 001 0. 001 Distillation, 0.:

1 Method AFNOR N.F.T 60.105. 2 Method AFNOR N.F.T. 60.105. 3 MethodAFNOR N.F.M. 07.009.

The catalyst may be employed as a fixed bed, a moving bed, or in thefluidized state.

The degree of reduction in pour point is a function of the catalystactivity and in the case of a fixed bed process, in which the catalystis not continuously regenerated, the greatest reduction in pour point isobtained during the early stages of a processing period. In suchcircumstances, the operating temperature may be gradually increased tocompensate for loss of activity. Alternatively, continuous catalystregeneration may be employed, using either a moving or fluidizedcatalyst bed process.

If desired, a part only of a particular distillate may be treated by theprocess according to the invention and the resulting product blendedwith the untreated portion of the distillate to give a final product ofreduced pour point.

It has been discovered that it is desirable to maintain a certainhydrogen partial pressure for any particular feedstock and that thedegree of conversion falls off if the hydrogen partial pressure fallsbelow this minimum even if the total pressure is maintained. The optimumvalues for the hydrogen partial pressure and the hydrogen to hydrocarbonratio depend upon the nature of the feedstock. For example, theseconditions are compared in the following table, No. 2, for a light gasoil having an I.B.P. of 220 C., an F.B.P. of 400 C. and a pour point of1 C. and a heavy gas oil having an I.B.P. of 290 C., an F.B.P. of 390C., and a pour point of +17 C.

Table 2 Partial "H /IL, Ratio Pressure of increasing the total pressureand this effect is illustrated by the results set out in Table No. 3.

Satisfactory treatment of a heavy gas oil at constant pressure may beachieved by adding between 20 and by volume of a lower boilingdistillate such as kerosine to the heavy gas oil. An example of thismethod of operation is illustrated by the results set out in Table No.4.

A silica-alumina base suitable for preparing a catalyst for use inaccordance with the present invention may be made in a variety of ways.

According to one method, the silica gel is precipitated in situ in thepores of the alumina by hydrolyzing a silicon compound with which thealumina is impregnated. The silicon compound may be organic or inorganicand suitable compounds include ethyl silicate, trichlorosilane andtetrasilane. It is advantageous to add to the ethyl silicate, forexample, a sufficient quantity of alcohol to saturate the alumina almostcompletely to ensure homogeneous distribution of the silicate in thealumina. Ethyl, methyl and other alcohols may be used for this purpose.Finally, the silicate is hydrolyzed by means of acidified water and theformation of the gel assisted by the addition of ammoniacal water. Thesilica-alumina composite is then dried and calcined. The following is aspecific example of preparing a silica-alumina base by this method:

EXAMPLE In order to obtain 1,110 g. of a support having 10% silica, asolution was prepared containing 330 g. of ethyl silicate (30% SiO andcc. of methanol. 1 kg. of alumina granules calcined between 200 and 800C. were slowly wetted with this solution while stirring and afterseveral minutes to allow homogeneous impregnation, the granules werewashed with 100 cc. of water containing 10% HCl. After several hours,the granules were washed with 100 cc. of ammoniacal water and thencalcined at about 450 C.

'Table 3 [Catalyst AA3: S102 8.9%, M003 10.64%, C 0.55%, 2 HydrogenPartial Pressure, 55 kgJomfl; Space Velocity, 1 v./v./hr.

Operating Conditions Hydrogen/Hydrocarbon Ratio=10l1 moles/moleTemperatures, C 430 440 456 Pressure, kgjcm. 73 73 73 74 74 76 77. 577.5 80 82 82 HOS 32 56 80 104 123 152 176 206 224 243 272 296 FeedstockHeavy Gas Oil Density at 15 0 881 342 342 342 343 844 346 349 846 347347 347 343 Pour Point, 0--.. +17 +8 +8 +5 +5 +5 +3 +11 +5 +5 +5 +3 +5016110 Point, 0---- +24 +11 +11 +9 +9 +10 +13 +15 +9 +9 +11 +11 +11Paraflins, Percent wt. 13. 3 9. 7 Distillations ASTM, 0

1.13.1 273 136 143 139 136 142 136 134 145 145 133 137 145 5%." 312 162180 176 176 135 177 179 135 135 130 174 133 56%. 375 332 333 324 317 236326 331 325 325 326 321 327 90%. 400 394 406 332 374 390 332 396 336 337336 393- 333 95%. 460 397 333 395 399 19.133-.-" 400 400 400 406 406 400466 400 406 400 460 460 466 Yield, Percent w Gas 0 92.5 91.9 39.7 90.891.4 92.7 91.3 39.3 33.7 89.6 90.6 96.4 Gasoline 1.3 2. 3.2 2.1 2 1.92.7 4.4 2.9 2.7 2.3 H, Consumption, set/16161 224 236 245 232 212 232274 264 246 234 206 266 Table 4 A more economic method of preparing asuitable silicaloamyst M3 (See Table 3)] alumina base consists inextruding an intimate mixture of silica gel and alumma. The silica maybe prepared Operating Conditions.

Pressure 76 kgjcmfi 1n known manner from sod1um sllrcate and 1s washedwith Space Velocity 1 v./v. hr. Ratio 01112110 Hydr0carbon=12/1moles/mole sulfur acid to remove sod1um. The silica gel is thenTemperature, 440 0. mixed with the alumina and the mixture extruded toform extrudates of between 2 and 2.75 mm. diameter. Two HOS Kero- HeavyMix- 32 56 particularly effective catalysts prepared in this way had meGas 011 me the following percentage compositions by weight.

Density at 15 0 792 375 359 334 333 Pour Point, o C +20 +15 35 Catalyst1 Catalyst?! Cloud Point, C... +22 +18 6 +5 Distillation ASTM, 0.: 8.913.3 I,B,P 184 222 194 145 147 0 7 1 7 32 31 a 32 015 211 466 399 367364 balance balance 216 380 373 233 466 466 339 390 Various resultsobtained using catalysts having bases prepared in the manner justdescribed are set out in Mixture: 32.7 33 .7 Tables 6, 7 and 8. 28% 1,3: gggffg on 3g 6 It is important for the temperature and spacevelocity to be correctly correlated if a satisfactory reduction in Theresults obtained on treating a heavy gas oil using catalysts havingbases prepared by the method just described are set out in Table 5. Thistable also illustrates the eifect of varying the silica content of thebase. It will be seen that the results obtained with a 20% silica baseare markedly inferior to those obtined with a 15% silica base and ingeneral it has been found that the content of silica should not exceed14% by weight of the total catalyst. 90% alumina.

Table 5 Operating Conditions: Hydrogen to Hydrocarbon ratio=7.5:1;Pressure, 1000 p.s.i.g.; Space Velocity, 1 v./v./hr. Cataly L68 1135,20% Sili- L68 A22, 15% Silica in Base L58 A17, 10% Silica in Base ea inBase Temperatures, C 420 430 440 420 425 430 420 l 425 430 FeedstockDensity at 15 C 869 828 823 823 826 825 827 826 829 Pour Point, C... +11+2 1 --4 4 4 1 1 Cloud Point, O +13 +5 1 0 1 0 +2 0 +1 Parafiins,Percent wt... 13.8 8.5 9.1 10. 7 Distillations ASTM,

PI 248 70 70 70 70 70 70 5% 297 125 125 109 130 130 131 50% 352 323 314314 323 322 32 1 388 367 369 373 377 376 375 400 374 385 389 394 392 399P F 1 '400 376 392 395 398 394 399 Yield, Percent wt 96 96 98 99 98 99The above catalysts had the following composition:

L68 11.35: 17.7% S10 10.64% M003, 0.55% 000, 71.11% A L68 11.22: 133%S102, 10.64% M003, 0.55% COO, 75.51% A190 11.68 14.17: 8.9% S102, 10.64%M003, 0.55% 000, 79.91% A 7 8 Table 6 Operating Conditions: Pressure, 40kg./e1n. Space Velocity, 1 v./v./l1r.; Hydrogen to Hydrocarbon ratio,7.5:1; Platiormer Hydrogen Catalyst L68 A37, 5% Silica in Base L.6811.38, Silica in Base Temperatures, C 400 420 430 400 420 430 Density/4, C 816 811 809 Pour Point, C... 10 22 -22 Cloud Point, C 4 l5 l8Distillation, C:

I.B.P 70 70 5%-. 205 130 282 270 90%. 342 334 95%". 357 357 F.B. 371 360Yield, Percent wt 99 98 Catalyst composition:

L.68 A37: 4.4% SiOz, 10.64% M003, 0.55% C00, 84.41% A1203. L68 A38: 8.9%S102, 10.64% M00 0.55% 000, 79.91% A1203.

Table 7 [Catalyst A.44: 8.9% SiOz, 10.64% M003, 0.55% 000, 79.91% A1 03]Operating Conditions: 8.9% Silica as gel;

Hydrogen to Hydrocarbon rzlitioi 771511; 79.9% wt. Alumina, 10.7% wt v.v. r.

Pressure, kgn/crn.

Temperature, C

Table 8 Operating Conditions: Pressure, 70 kgjcnlfl; Space Velocity, 1v./v./hr.; Hydrogen to Hydrocarbon ratio, 7.5:1 Catalyst L68 A.5l, 2111m., 15% Mieroporous Silica Gel L.68 A.52, 95 2.15 I1'1l11., 15%Mieroporous Silica in Base Gel in Base Temperature, C 420 430 440 420430 440 Feedstock Density at 15 C 809 822 815 819 814 810 810 810 819815 814 813 815 Your Point, C. +11 +1 10 4 13 --10 10 +4 7 4 --13 10 7Cloud Point, 0 +13 +2 6 3 10 8 -8 3 4 4 9 8 5 Paralfins, Percent wt 13.8 3. 7 1 Distillation ASTM, 0:

PI 248 70 70 70 7O 70 70 70 70 70 70 70 70 5% 297 125 76 105 103 102 9898 114 116 100 94 104 50%.- 352 302 290 300 287 288 283 303 300 306 291287 296 388 374 353 360 357 357 354 359 362 363 357 357 358 95%.- 400387 364 365 370 375 369 371 378 379 309 370 373 PF 400 388 379 378 370383 380 384 381 382 377 378 381 Yield, Percent wt 98 97 97 96 96 9G 9597 97 96 96 98 Catalyst composition:

} 13.3% SiOz, 10.64% M003, 0.55% 000, 75.51% A1103.

Table 9 [Catalyst 14.43 (see Table 3)] Temperature, C 415 390 390 390360 415 390 Pressure, kg/cm. 35 70 55 40 70 H l./h 100 100 60 100 100120 80 160 Space Velocity, v.lv./l1r 5 5 7 3 5 5 8 6 4 8 FeedstockDensity at 15 C 1. 869 851 854 854 851 858 852 856 Pour Point, O +11 +11+11 +11 +11 +11 +11 +11 Cloud Point, 0- +13 +12 +12 +12 +12 +12 +12 +12Sulphur, Percent W 1. 6 0.36 0. 57 0. 74 0.30 O. 9" 0. 40 0.76Distillations ASTM,

I.B.P S0 270 340 383 393 400 What we claim is:

1. A process for the treatment of distillate petroleum fractions boilingwithin the range 150-450 C. to lower the pour point at least C. withoutmaterial reduction in the specific gravity and diesel index of saiddistillate fractions, comprising contacting the distillate fraction asfeedstock in a treating zone and in the presence of hydrogen with adehydrogenation catalyst on a silica-alumina base whose silica contentis in the range 5 to 14% by Weight of total catalyst, the hydrogen tohydrocarbon mole ratio being from 5 to 1 to 20 to 1; maintaining aselected temperature and a selected space velocity in said zone, saidselected temperature in said zone being maintained at least about 400 C.but not higher than about 480 C. and being a temperature at which, atsaid selected space velocity, not more than 20% wt. of the feedstock isconverted to material boiling below 150 C. and said selected spacevelocity being at least equal to the space velocity at which at saidselected temperature not more than 20% wt. of the feedstock is convertedto material boiling below 150 C. but not exceeding 3.0 v./v./hr.;maintaining a selected pressure in said zone in the range 100-1500p.s.i. ga., said selected temperature and said selected space velocitybeing correlated to reduce the pour point of the feedstock such that thepour point of the material of the treated distillate fraction boilingabove 150 C. is at least 5 lower than the pour point of the feedstock,and recovering the treated distillate fraction.

2. A process according to claim 1, wherein the temperature within saidtemperature range is such that not more than 15% wt. of the feedstock isconverted to material boiling below 150 C.

3. A process according to claim 1, wherein the feedstock consists of aheavy gas oil in admixture with to 100% by volume of a lower boilingdistillate such as kerosine.

4. A process according to claim 1, wherein the silica content has beenderived fiom a silicon compound with which the alumina has beenimpregnated.

5. A process according to claim 4, wherein said silicon compound isethyl silicate.

6. A process according to claim 1, wherein the silicaalumina base of thecatalyst consists of a mixture of preformed alumina and silica.

7. A process according to claim 1 wherein the pressure is above theequilibrium pressure of the feedstock at the particular combination ofcorrelated temperature and 10 space velocity, whereby reduction of thediesel index is at least minimized.

8. A process for the treatment of distillate petroleum fractions boilingwithin the range ISO-450 C. to lower the pour point at least 5 C.without material reduction in the specific gravity and diesel index ofsaid distillate fractions, comprising contacting the distillate fractionas feedstock in a treating zone in the presence of hydrogen with acatalyst consisting essentially of 5-15 by weight of molybdenum trioxidesupported on a silica-alumina base, the silica content being in therange 5-14% by weight of total catalyst, the hydrogen to hydrocarbonmole ratio being from 5 to 1 to 20 to 1; maintaining a selectedtemperature and a selected space velocity in said zone, said selectedtemperature in said zone being maintained at least about 400 C. but nothigher than about 480 C. and being a temperature at which, at saidselected space velocity, not more than 20% wt. of the feedstock isconverted to material boiling below C., and said selected space velocitybeing at least equal to the space velocity at which at said selectedtemperature not more than 20% wt. of the feedstock is converted tomaterial boiling below 150 C. but not exceeding 3.0 v./v./hr.;maintaining a selected pressure in said zone which is greater than theequilibrium pressure of the feedstock at said selected contactingtemperature and said selected space velocity but not greater than about1500 p.s.i. ga., said selected temperature and said selected spacevelocity being correlated to reduce the pour point of the feedstock suchthat the pour point of the material of the treated distillate fractionboiling above 150 C. is at least 5 C. lower than the pour point of thefeedstock, and recovering the treated distillate fraction.

9. A process according to claim 8, wherein the molybdenum oxide contentis 10 to 11%.

10. A process in accordance with claim 8 wherein the catalyst furtherincludes cobalt oxide in an amount of .2-1% by weight with themolybdenum trioxide being present in an amount of 5 to 15%.

11. A process according to claim 10, wherein the molar ratio of themetals Co to M0 is 0.1.

References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 125,509Marchv 17, 1964 Bernard Laine et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below Column 1, line 43, for "catalyt'! read catalyst column5, line 51, for "obtined" read obtained column 6, line 29, for "sulfuracid" read sulfuric acid line 48, for "aof" read of Signed and sealedthis 15th day of September 1964,,

(SEAL) Attest:

ERNEST W. SWIDER- EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A PROCESS FOR THE TREATMENT OF DISTILLATE PETROLEUM FRACTIONS BOILINGWITHIN THE RANGE 150-450*C. TO LOWER THE POUR POINT AT LEAST 5*C.WITHOUT MATERIAL REDUCTION IN THE SPECIFIC GRAVITY AND DIESEL INDEX OFSAID DISTILLATE FRACTIONS, COMPRISING CONTACTING THE DISTILLATE FRACTIONAS FEEDSTOCK IN A TREATING ZONE AND IN THE PRESENCE OF HYDROGEN WITH ADEHYDROGENATION CATALYST ON A SILICA-ALUMINA BASE WHOSE SILICA CONTENTIS IN THE RANGE 5 TO 14% BY WEIGHT OF TOTAL CATALYST, THE HYDROGEN TOHYDROCARBON MOLE RATIO BEING FROM 5 TO 1 TO 20 TO 1; MAINTAINING ASELECTED TEMPERATURE AND A SELECTED SPACE VELOCITY IN SAID ZONE, SAIDSELECTED TEMPERATURE IN SAID ZONE BEING MAINTAINED AT LEAST ABOUT 400*C.BUT NOT HIGHER THAN ABOUT 480*C. AND BEING A TEMPERATURE AT WHICH, ATSAID SELECTED SPACE VELOCITY, NOT MORE THAN 20% WT. OF THE FEEDSTOCK ISCONVERTED TO MATERIAL BOILING BELOW 150*C. AND SAID SELECTED SPACEVELOCITY BEING AT LEAST EQUAL TO THE SPACE VELOCITY AT WHICH AT SAIDSELECTED TEMPERATURE NOT MORE THAN 20% WT. OF THE FEEDSTOCK IS CONVERTEDTO MATERIAL BOILING BELOW 150*C. BUT NOT EXCEEDING 3.0V./V./HR.;MAINTAINING A SELECTED PRESSURE IN SAID ZONE IN THE RANGE 100-1500P.S.I. GA., SAID SELECTED TEMPERATURE AND SAID SELECTED SPACE VELOCITYBEING CORRELATED TO REDUCE THE POUR POINT OF THE FEEDSTOCK SUCH THAT THEPOUR POINT OF THE MATERIAL OF THE TREATED DISTILLATE FRACTION BOILINGABOVE 150*C. IS AT LEAST 5*C. LOWER THAN THE POUR POINT OF THEFEEDSTOCK, AND RECOVERING THE TREATED DISTILLATE FRACTION.